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Mussels secrete a powerful adhesive to hold tight on rocks swept by violent waves - and a synthetic version could prove critical for surgery and cancer treatment, say researchers.

Scientists have created materials that mimic the mussels' sticky proteins and could have medical applications such as sealants for foetal membrane repair, self-setting antibacterial hydrogels and polymers for to deliver cancer drugs and destroy cancer cells.

"An inland stream with water moving at only one metre per second is very hard to stand in," says University of Washington biologist Emily Carrington, who studies the tiny molluscs.

"Imagine something going 10 times that speed - over your whole body."

That's what mussels withstand - and more - as they cling to rocks, grasses and other materials under water.

Carrington says water travelling 10 metres per second would be equivalent to winds blowing 965 kilometres per hour.

The "glue" comes from the mussel's foot, called the byssus, which can cling to almost any surface - wet, dry, organic or inorganic.

Phillip Messersmith, professor of biomedical engineering at Northwestern University, who presented another paper, is researching how to reproduce the sticking power in a synthetic substance.

He and his team have developed a version that is equally water resistant, and could help close internal wounds, among other medical applications.

"The repair or reconstruction of tissues in the human body, where water is ubiquitous and its presence represents a challenge for achieving desired outcomes," is an especially compelling potential use for the adhesive, says Messersmith.

For instance, the substance could prove useful in repairing fetal membranes that have prematurely ruptured, a condition that is difficult to treat and can lead to miscarriage, premature births and other serious complications.

Messersmith and his team are collaborating with researchers in Europe on clinical trials.

Another team is working to develop synthetic versions of the mussel's adhesive that could help repair broken bones or teeth.

"These glues are tolerated by the body and are water-resistant and that is perfect for making repairs inside the body," he says.

Environmental changes

In addition to the medical applications, Carrington's team uses the mussel "glue" as an indicator of changes in the environment - especially of warming.

Laboratory experiments showed that mussels are significantly less able hold on when the temperature rises.

The resistance of these fibres, strongest in waters 10 to 18°C, diminishes by 60 per cent when the water reaches 8.3°C (15°F) above typical summer temperatures in the mussels' place of origin.

Researchers had already observed that the mussel's foot weakened at the end of summer and in early autumn, just when storm season in the US reaches full force, before regaining strength in the colder seasons.

"We're trying to learn what causes this seasonal weakening - is it related to warmer weather, their spawning cycle or something else?" asks Carrington.

"And now we want to know if increased environmental fluctuations will help put them over the edge.